1. Field of the Invention
The present invention relates to imaging apparatuses, information processing apparatuses and methods, and computer programs therefor. More particularly, the present invention relates to an imaging apparatus, such as a digital camera, including position estimating units employing different techniques, in which items of position information individually obtained by the position estimating units are evaluated, and, position information determined to be more accurate is selectively used, an information processing apparatus and method, and a computer program therefor.
The present invention further relates to an imaging apparatus including, as position estimating units using different techniques, for example, a position estimating unit based on the Global Positioning System (GPS) and a position estimating unit based on detection information of access points (APs) serving as wireless communication base stations, in which position estimation results individually obtained by the position estimating units are evaluated, and position information is used in a manner that, for example, highly evaluated result data is used as attribute data of captured image data, an information processing apparatus and method, and a computer program therefor.
2. Description of the Related Art
Nowadays, imaging apparatuses such as digital cameras have become highly sophisticated. For example, some imaging apparatuses have the GPS function to obtain position information using GPS and record the obtained position information as attribute information of captured image data.
In order to obtain position information using GPS, an imaging apparatus is necessary to be able to receive radio waves from satellites. When beneath the ground, for example, the imaging apparatus is incapable of receiving radio waves from satellites and hence incapable of obtaining position information. In order to obtain position information using GPS, the imaging apparatus is necessary to perform a satellite acquisition process as an initial process, which takes time. That is, when a turned-off camera is switched on, the camera is incapable of immediately obtaining position information using GPS.
In order to reduce a wait time before position information is obtained, one method is available in which a GPS module of a camera is maintained in an operating state, and navigation messages from satellites are continuously received using the GPS module. The received navigation messages are stored in a storage unit, and satellite acquisition is performed using the stored navigation messages. The effective period of almanac data contained in the navigation messages is set to three months, and the effective period of ephemeris data contained in the navigation messages is set to two hours. Navigation messages stored in the storage unit are necessary to be updated one after another. Thus, a continuous message reception process is necessary to be performed.
A structure that can continuously receive navigation messages can update navigation messages recorded in a storage unit in a steady manner. Quick satellite acquisition using navigation messages (almanac data and ephemeris data) within the effective period can thus be performed. However, when no data within the effective period is recorded, efficient satellite acquisition using the data is difficult to be performed. Thus, a satellite acquisition process involving a relatively long processing time is necessary to be performed. As a result, the time from activation of the GPS module to the obtaining of position information becomes very long, and hence, position information is difficult to be obtained in a timely manner.
When a camera with a GPS module performs a process of adding position information obtained using the GPS module as attribute information of captured image data, it is necessary to obtain position information at the time an image is captured by a user. However, as has been described above, in an environment where position information is difficult to be obtained from satellites using GPS or when position information is difficult to be immediately obtained from satellites using GPS, accurate position information corresponding to captured image data is difficult to be obtained.
One of position estimation methods using techniques other than those using GPS is described in Japanese Unexamined Patent Application Publication No. 2002-107443. This method concerns a wireless communication system in which a mobile device estimates its position by measuring the intensity of radio waves received from a base station whose position information has been registered in advance. In such a configuration where the position is measured using the base station, the mobile device is incapable of measuring the position when the mobile device is in an area where the mobile device is incapable of communicating with the base station whose position information has been registered.